The invention relates to a device for pairwise coupling of systems for window covering, which are each provided with at least one rotatable shaft for winding up or unwinding the window covering. The device comprises a first part (10) adapted for connection to the winding shaft of a first system, a second part (20) adapted for connection to the winding shaft of a second system, wherein the first and second parts are rotatable relative to each other and wherein the first part and the second part are provided with co-acting adjusting means which are adapted to adjust the winding shaft of the second system relative to the winding shaft of the first system over a desired angle of adjustment, and to fix the winding shaft of the second system in the corresponding position. The adjusting means comprise a worm wheel transmission, wherein the worm screw (11) forms part of the first part (10) and the worm wheel (21) forms part of the second part (20).